The problem is most likely to occur when the map data set contains polygons that are defined with fewer than three points.

To circumvent the problem, remove these invalid polygons from the data. Refer to the Full Code tab for example code.

Operating System and Release Information

data gps;
   input longitude latitude site $;
   x=longitude*arcos(-1)/180;
   x=x*(-1);
   y=latitude*arcos(-1)/180;
   datalines;
-77.0348 40.0454 a
-78.4437 39.1623 b
-78.4115 39.3751 c
-78.7646 40.6354 d
;
run;

proc freq data=maps.counties noprint;
   tables state*county*segment / out=counts(where=(count < 3));
run;

data counties;
   merge maps.counties counts(in=a);
   by state county segment;
   if a then delete;
run;

proc ginside data=gps map=counties out=gpscounties;
   id state county;
run;

proc sort data=gpscounties;
   by site;
run;

proc print data=gpscounties;
   var site state county x y;
run;